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Flame retardant
The danger posed by combustible textiles fueled the search for flame resistance. As early as 1735,
Obadiah Wyld received a patent in Great Britain for developing a flame retardant mixture of alum,
ferrous sulfate, and borax. Studies continued in the 19th century in which various agents were used
in the search for flame resistance. While some success was achieved, most attempts eventually failed
because most of the agents, often inorganic salts, were water soluble and would wash out of the fabric.
The one exception was the work of chemist William Henry Perkins who developed the "Non-flam" process
using stannic oxide. In 1912 he claimed that garments treated with stannic oxide were flame resistant
and stood up to two years of use with weekly washing. The initial impetus for research at the Southern Regional Research Center into flame resistant cotton
fabrics came from the Army's Quartermaster Corps, which was seeking fire retardant uniforms. At the
same time, people in the cotton industry understood that there would be consumer demand for flame
retardant textiles if they could be made durable and if the fabrics could overcome the stiffness and
roughness that characterized early attempts. Research at SRRC focused on the chemical modification of cotton by the chemical reaction of flame retardants
with the cellulose molecules on the surface and within the cotton fiber. Wilson Reeves and J.D. Guthrie led
research into the durable flame retardant tetrakis(hydroxymethyl)phosphonium chloride (THPC), which
unfortunately had the disadvantage of a significant loss in fabric strength. To counter this problem,
scientists raised the pH of THPC with aqueous sodium hydroxide, creating THPOH [tris(hydroxymethyl)phosphonium
hydroxide]. This process resulted in fabrics which were less stiff and stronger. THPC and THPOH were both treated
with bromine compounds and ammonia in an attempt to produce flame retardant fabrics that were light weight and
had a good "hand," that is were soft. Other additives that were used included APO [tris(aziridinyl)phosphine oxide] and nitrogen combined with
phosphorous. Combinations of these reagents with THPC and THPOH were tried as well. The combination of
APO and THPC proved to be one of the most effective flame retardants because the properties of the fabric
remained good. Unfortunately, APO is expensive and toxic, so it could not be used commercially. SRRC research results in flame retardant cotton and blends are used by the military in various projects to
provide U.S. service men and women with the best protective clothing possible. Some of the materials produced
were used by NASA in early space flights and by fire departments throughout the country. The many publications
by SRRC scientists kept focus on the dangers of performing risky operations at high temperatures without the use
of specialized flame retardant fabrics and undoubtedly resulted in the saving of lives and property.
Cotton under attack |
Cotton and science |
Durable press |
Flame retardant
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